In the technical fields of performing measurements or recording and reproducing information by using laser light, multi-wavelength integrated semiconductor laser devices have been used for emitting a plurality of laser beams of different wavelengths.
For example, in a measuring instrument intended for biometrics, a multi-wavelength integrated semiconductor laser device is used to irradiate biological substances with laser beams of different wavelengths. Fluorescence caused by biological reactions is detected to measure trace substances, immunogenic properties, and the like inside the living body optically.
Information recording and reproducing apparatuses and the like having compatibility with recording media of different recording and reproduction systems, such as DVD (Digital Versatile Disc) and CD (Compact Disc), have a pickup unit on which a multi-wavelength integrated semiconductor laser is mounted. Laser beams having predetermined wavelengths suited to respective recording media are emitted for compatible information recording and reproduction.
Among conventional multi-wavelength integrated semiconductor laser devices to be mounted on the pickup unit is one disclosed in patent document 1.
This conventional multi-wavelength integrated semiconductor laser device has a structure intended for miniaturization. As shown in FIGS. 1(A) and 2 of the document, electrodes 14 are formed at predetermined ends of separate semiconductor light-emitting elements 1 and 3 having different resonator lengths (at the ends closer to respective light-emitting points 2 and 4). Soldering metal 26 interposed therebetween is heat bonded to integrate the semiconductor light-emitting elements 1 and 3 with each other, thereby achieving a multi-wavelength integrated semiconductor laser device as a single member.
This structure provides the effect that the light-emitting points 2 and 4 can be located at a distance (emission point distance) W as close as 100 μm or less (around 72 μm). It is described that recording media of different recording and reproducing systems, such as DVD and CD or CD-R, can thus be irradiated with the laser beams through a single optical path, which allows simplification and miniaturization of the apparatus configuration.
[Patent document 1] Japanese Patent Application Laid-Open No. Hei 11-112091.